Asphaltic-paving composition



1 qualities of the asphalt, whereb even though fine Patented June 28, 1927.

UNITED STATES 1,634,241 PATENT OFFICE.

CHARLES N. FORREST, OF RAHWAY, NEW JERSEY, ASSIGNOB TO THE BARBER AS: PHALT COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION 0] WEST VIRGINIA.

Ho Drawing.

My invention relates to a novel asphaltic paving composition to be used in the manufacture or repair of asphaltic paving, and particularly as a wearing surface for asphalt streets or roads.

The object of my invention is to make the known asphalt paving compositions more tough and stable than has heretofore been possible, without diminution of the binding the composition may the better withstan the effects of traific without rutting, waving or other displacement.

I attain this object by intimately ,combining with the asphalt a salt of acetic acid which is fusible at the temperatures used for refining or fluxing the asphalt or for mixing it with its aggregate.

Attempts have been made to improve the stability of asphaltic compositions by adding thereto certain salts, such as copper sulphate,

zinc chloride, etc., but these salts are not fus-.

ible at the temperatures used in the treatment of asphaltic compositions, and 'conse uently y powdered do not econ e sufliciently difiused in the asphalt composition to well accomplish the desired resu t.

I have discovered, however, that the result desired is accomplished-b using for this purpose a salt of acetic aci' such for exas sodiumacetate, which is fusible,

amgile an therefore, ditfusible throughout the composition, by reason of the fact that its melting point is within the range of tem-' eratures to which asphalt is and may safely be subjected in the process of refining or fluxing it, or of combining it with its aggregate.

The temperatures ordinarily used in the manufacture of asphalt paving cements run from300 to 450 F. The melting point of sodium acetate is approximately 136 F., so that this salt is very suitable for the purpose,

In the practice of my invention I have found that the addition to the asphalt of from 1 to 5% b Wei ht of sodium acetate exerts a,beneficia stabi izing and toughening efi'ect upon the asphalt causing a considerable change in its softening point and decreasing its plasticity.

The sodium acetate may be added directly to the melted as halt cement, or to the combined melted asp ialt cement and hot mineral aggregate during the mixing of the paving ASPHALTIO-PAVING oomrosrrrox.

Application filed April 22, 1925. Serial No. 25,138.

mixture in the customary manner. In either event, the acetate melts and is thus brought into intimate contact with the liquid bitumen, water and other volatile constituents are expelled, and the anhydrous sodium acetate remains in the asphalt or mixture with the beneficial efiects' described. The mixing operation is completed in the course of one to -two minutes.

'On account of the reduction in plasticity of the asphalt cement by this treatment, the entire pavingmixture is so tou hened and stabilized that it sustains tra c without marking or displacement, while the same asphalt and mineral aggregate employed without this type of chemicaltreatment is inferior in these respects.

The sodium acetate may be added to any of the customarily used asphaltic aving cements, and with the cement thus sta ilized and toughened may be combined any of the customarily used mineral aggregates. the sake of example, however, I will indicate typical proportionments which may be used for both a sand and stone aggregate.

Sand.

Pounds. Asphalt cement 9-18 Sodium acetate 0. 27-0. 54 Stone dust 9 20 Graded sand 100 to 8 mesh 81.73-61.46

, Stone.

- Pounds. Asphalt cement 5-10. Sodium acetate 0. 15-0. 30 Stone dust 5-15' Graded stone 100 mesh to 1 inch 89. 85-74. 70

For t 

